Punch mechanism

ABSTRACT

A punch mechanism including a line of punches each having an interposer disposed between it and reciprocating drive mechanism. The interposers are reciprocably disposed in slots in a guide block, being pivoted therein by virtue of end walls of the slots acting on the edges of the interposers. A pneumatic piston is provided for moving each of the interposers into alignment with the drive mechanism to cause a punching action, and permanent magnets are provided for moving and holding the interposers in their inactive positions.

United States Patent Berkman et al.

[ 51 May 2,1972

[54] PUNCH MECHANISM [72] Inventors: John W. Berkman, Oronoco; LawrenceR.

Gravell, Rochester, both of Minn.

[73] Assignee: International Business Machines Corporation, Armonk, NYv

[22] Filed: Mar. 26, 1970 [21] App1.No 22,961

[52] U.S.Cl I ..234/ll4, 83/571 [51] Int. Cl. i 1 .G06k 1/02 [58]FieldofSearch. ..234/109,111,114,115,117,

[56] References Cited UNITED STATES PATENTS 3,412,932 11/1968 Mastersonet a1 ..234/l15 3,291,388 12/1966 Pataki ..234/115 3,311,297 3/1967Williams et al.. ...234/114 3,059,844 10/1962 Englund ...234/1153,394,882 7/1968 Cattorini et a1 .234/119 Primary E.\uniilierjames M.Meister Anomey-Hunitin & Jancin and Keith T. Bleuer [57] ABSTRACT Apunch mechanism including a line of punches each having an interposerdisposed between it and reciprocating drive mechanism. The intcrposersare reciprocably disposed in slots in a guide block, being pivotedtherein by virtue of end walls of the slots acting on the edges of theinterposers. A pneumatic piston is provided for moving each of theinterposers into alignment with the drive mechanism to cause a punchingaction, and permanent magnets are provided for moving and holding theinterposers in their inactive positions 14 Claims, 4 Drawing FiguresPatented May 2, 1972 2 Sheets-Sheet l ATTORNEY Patented May 2, 1972 2Sheets-Sheet 2 FIG.3

PUNCH MECHANISM BACKGROUND OF THE INVENTION 1. Field of the InventionThe invention relates to punch mechanism and particularly to suchmechanism designed for punching lines of holes in document cards whichrepresent data in coded form.

2. Description of the Prior Art It has been previously proposed in apatent to Jacob Rabinow, US. Pat. No. 3,104,053, that punches fordocurnents may be electrically controlled and in particular that each ofa plurality of punches shall have a magnet effective on it for movingthe punches laterally as well as longitudinally. Some of the punchesdescribed in this patent are permanent magnets.

The patent to Masterson, US. Pat. No. 3,411,709, also describes the useof pennanent magnets in punch mechanism; and these magnets are effectiveon reciprocating interposers and tend to move the interposers out ofmotion-transmitting relationship with respect to reciprocable punches.Bucking windings are utilized on the permanent magnets for the purposeof allowing the interposers to move into motion-transmittingrelationship with the respective punches.

It has also been proposed in the co-pending application of Baker et al,Ser. Number 746,514, filed July 22, 1968, for Electro-MechanicalActuator, that flexible interposers movable into line with punches maybe actuated by separate interposer link which in turn are actuated byelectromagnets.

SUMMARY OF THE INVENTION It is a general object of the present inventionto provide an improved low-cost, simple, and reliable punch mechanism.

More particularly, it is an object of the present invention to provideimproved punch mechanism which includes pivotally movable interposersheld in and movable into retracted nonpunching position by means ofpermanent magnets, with the retracting action of the magnets beingovercome by interposer actuators such as pneumatic pistons.

It is still another object of the invention to provide an improvedpunching mechanism of this type in which the actuators are free floatingwithin slots provided in a guide block so that relatively complicatedconnections need not be provided between the interposers and therespective punches.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view ofpunch mechanism incorporating the principles of the invention;

FIG. 2 is a side elevational view of the punch mechanism with portionsof it being broken away to more clearly reveal internal parts of themechanism; and

FIGS. 3 and 4 are respectively sectional views taken on line 3-3 and 44of FIG. 1.

DETAILED DESCRIPTION Referring now to the drawings, the illustratedpunch mechanism may be seen to comprise, in general, a housing 10, astripper 12 disposed on the housing 10, a die 14 overlying the stripper12, a die stiffener and support 16 with respect to which the die 14 isfixed, a plurality of punches 18 extending in a row through the stripper12, a guide block 20 having a plurality of interposers 22 disposedtherein, a pair of permanent magnets 24 and 26 disposed in the block 20,a plurality of pneumatically actuated pistons 28 and 29 in the block 20,an eccentric shaft 30 rotatably disposed in the housing 10, a bail 32adapted to abut the interposers 22 for driving them upwardly and alsofor pulling the punches l8 downwardly, and drive mechanism 34 forreciprocating the bail 32 vertically.

The housing carries bushings 36 in which the shaft 30 is rotatablydisposed. The drive mechanism 34 comprises a pair of yokes 38 eachhaving an oblong opening 40 with flatted sides 40a. A bearing 42 isdisposed in each of the openings 40 and has flatted sides 42a in slidingcontact with the flatted sides 40a of the associated opening 40, and thebearing 42 is rotatably disposed on the round eccentric portion 30a ofthe shaft 30.

The bail 32 is fixed in the pair of yokes 38 and has an opening 32atherein for receiving the interposers 22. The lower edge 32b of theopening 32a, as will hereinafter appear, constitutes an abutting edgefor the interposers 22; and the bail is provided with laterallyextending portions 44 defined by slots 46 for embracing the punches 18.Each of the punches 18 has a land portion 18a of increased diameterunderlying a pair of the bail portions 44 so that the portions 44,cooperating with the land portions 18a of the punches 18, in effect havea oneway engagement with the punches 18 for retracting the punchesdownwardly as shown in the figures. The bail 32 is reciprocably disposedin bearing blocks 48 carried by the housing 10.

The guide block 20 is provided with a plurality of vertically extendingslots 50 interspaced with similar slots 52 which are offset with respectto the slots 50 as seen in FIG. 4. The slots 50 are each provided with adownwardly and outwardly extending side portion 50a and parallel sideportions or walls 50b and 500, and the slots 52 are each provided withsimilar side portions but the slots 52 are reversed with respect to theslots 50.

An interposer 22 is slidably disposed in each of the slots 50 and 52,and each of the interposers 22 is formed with a boss 54 on its upper endand with a notch 56 forming a horizontal ledge 56a adjacent the lowerend of the interposer. The interposers 22 are reversed in theconsecutive openings 50 and 52 so that the bosses 54 extend in onedirection in a slot 50 and the bosses 54 extend in the oppositedirection in the adjacent slot 52. Each of the interposers 22 is ofrigid magnetic material.

Each of the interposers 22 has an elongated opening 22a through it, anda rod 58 extends through the openings 22a of all of the interposers 22and into the ends of the guide block 20.

The guide block 20 is of nonmagnetic material, and the permanent magnets24 and 26 are embedded within guide block 20 in the positions shown. Itwill be noted that the magnets 24 and 26 extend parallel with the row ofpunches l8 and parallel with the interposers 22 which are in a similarrow. The magnets 24 and 26 are each magnetized so that their north andsouth poles appear on the long edges of the magnets 26 extending fromone side edge of the magnet to the other and perpendicular to thepunches l8; and, as shown in FIG. 1, the upper edges of the magnets 24and 26 constitute the north poles of the magnets. The magnets 24 and 26may, if desired, be reversed so that the north poles are on the bottom;or only one of the magnets 24 and 26 may be reversed so that the northpole of one magnet is at the top while the north pole of the othermagnet is at the bottom. It will be observed that the slots 50 arecloser to the magnet 24 than to the magnet 26; and, correspondingly, theslots 52 are closer to the magnet 26 than to the magnet 24.

Auxiliary housing portions 60 and 62 are fixed onto the guide block 20,and the pistons 28 and 29 are reciprocably disposed in cavities 64formed in the guide block 20 and in the portions 60 and 62. An opening600 extends through the housing 60 in communication with each of thecavities 64. Each of the pistons 28 has a rod portion 28a adapted tomake contact with one of the interpomrs 22 in a slot 50, and each of thepistons 29 has a similar rod portion 29a adapted to make contact with aninterposer 22 disposed in one of the slots 52. A flexible diaphragm 66is fixed between the guide block 20 and the housing portion 60, and asimilar diaphragm is fixed between the guide block 20 and housingportion 62 for sealing the two sides of each of the cavities 64. It willbe observed from FIG. 3 that the pistons 28 are elongated verticallywith the major or long dimension of the pistons 28 extending parallelwith the interposers 22, and the cavities 64 are of a similar elongatedshape. The pistons 29 have the same shape as the pistons 28 with theirreceiving cavities 64 being of the same size and shape as the cavities64 for the pistons 28; and the pistons 28 and 29 alternate indisposition with respect to each other along the length of the guideblock 20, with a piston 28 having its rod portion 28a extending intoeach slot 50 and with the rod portions 29a of the pistons 29 extendinginto the interspaced slots 52. This offset arrangement of the pistons 28and 29, together with the oblong shapes of the pistons, allows thepiston rods 28a and 29a, and slots 50 and 52, and therefore theinterposers 22 and punches 18 to be located quite close together.

The stripper 12 has a row of vertical openings 68 therethrough withplastic bushings 70 in the openings for receiving the punches 18 whichare in a similar row. It is contemplated that there shall be sufficientfrictional force of each bushing 70 on the punch 18 therein so that thepunch 18 remains in its lowermost position even though the punch 18 andthe stripper 12 may both be of magnetic material and may thus both bemagnetized.

The die 14 has a row of die holes 140 therethrough which are inalignment with the openings in the bushings 70 so that the correspondingpunch 18 may enter the die hole 140 with a punching action. The support16 overlies much of the surface of the die 14 for supporting the die,and the support 16 is provided with a longitudinally extending slot 16atherein which is in communication with all of the openings 14a in thedie 14 and by means of which the punchings may be removed. The die 14 ismaintained with a small spacing from the stripper 12 by means of spacerplates 72 so that a record in the form of a document card 74, forexample, may be moved between the die 14 and stripper 12 when thepunches 18 are not in raised position.

In operation, the document card 74 is moved to a position beneath thedie openings 14a. At this time, one or more of the pistons 28 and 29 maybe actuated by means of air pressure supplied through the correspondingopening 600 onto the diaphragm 66 and the piston 28 or piston 29 locatedwithin the corresponding cavity 64. The shaft 30 is continuously driven;and the eccentric shaft portion 300, acting through the bearings 42 onthe horizontal sides 40a of the openings 40, causes the yokes 38 andthereby the bail 32 fixed to the yokes 38 to reciprocate verticallythebail 32 sliding in the bearing block 48. The interposer corresponding tothe piston 28 or piston 29, that has been actuated by means of airpressure, is thereby moved away from the edge 500 or corresponding edgein one of the slots 52 toward the center of the slot with the upper endof the interposer pivoting on the slot end walls 50b and 50c. The boss54 is rounded, as is the top edge of the interposer 22, to allow suchpivotal movement of the interposer 22 within the slot 50 or 52. Theabutment edge 56a of the interposer is thus moved in alignment with theedge 32b of the bail 32. The interposer 22 is therefore moved upwardlyon the next upward movement of the bail 32, and the interposer 22 movesthe corresponding punch 18 upwardly so that the punch enters thecorresponding die opening 140 and punches a corresponding hole in thedocument card 74. On the succeeding downward reciprocation of the bail32, the portions 44 of the bail embracing the punch 18 pull the punch 18downwardly by means of its land portion 18a out of punching relationshipwith respect to the corresponding die opening 140 so that the documentcard 74 may then be incremented into another punching relationship withrespect to the die openings 14a.

When air pressure is released from the corresponding piston 28 or 29,the corresponding magnet 24 or 26 pulls the interposer 22 back intoinoperative position, with the edge of the interposer 22 in bearingrelationship with respect to the outwardly flaring edge 50a of the slot50 or the corresponding outwardly flaring edge of the slot 52. Since theslots 50 and thereby the interposers 22 within these slots are locatedcloser to the magnet 24 than to the magnet 26, the magnet 24 iseffective to pull these interposers 22 back into inactive positions inwhich the ledges 560 are out of alignment with the edge 32b of the bail32 and in which the interposers are in contact with the outwardlyflaring side walls 500 of the slots 50. Likewise,

the magnet 26 is efiective on the interposers 22 within the slots 52 forretracting these interposers to inactive positions. Subsequently, whenany of the pistons 28 or 29 are actuated by air pressure, moving thepiston rods 28a and 29a into the corresponding slots 50 or 52, movementof the corresponding interposers 22 is against the action of the magnet24 or 26 that has previously retracted the interposers into inactivepositions and which yieldably holds the interposers in their inactivepositions.

The above-described punch mechanism is advantageously a very low-cost,simple, and reliable mechanism. Although the pneumatically actuatedpistons 28 and 29 are disclosed for moving the interposers 22 intopunching positions, it is apparent that electromagnetic actuators may beused instead of the pistons 28 and 29. The interposers 22 and thepunches 18 may be positioned very close together particularly in view ofthe fact that the pistons 28 and 29 are of elongate shape with theirgreatest dimensions in the vertical direction. Also, in order to providea substantial number of interposers 22 and punches 18 in line, half ofthe pistons (pistons 28) are provided on one side of the interposers andpunches while the other half of the pistons (pistons 29) are disposed onthe other side of the interposers and punches, the pistons 28 and 29 ineffect being alternated with respect to the interposers and punches.

in view of the fact that the interposers 22 are in sliding contact withand are thereby pivoted with respect to the vertical parallel side walls5% and 50c of the slots 50 and the corresponding side walls of the slots52 rather than actual pivots of the interposers on the punches 18 beingprovided, a lowcost and simple construction is assured in which theinterposers 22 are out of the way of bail 32 when punching is notintended. Advantageously, the interposers 22 have no movement whenpunching by the respective interposers is not intended, since theconstruction is such that the bail 32 only moves the interposers 22 whenthe ledges 56a are in alignment with the bail edge 32b. The interposersare effectively free floating in their slots 50 and 52 and are trappedin these slots in ordinary operation of the mechanism due to magneticaction of the magnets 24 and 26; and the magnets 24 and 26 which are inthe form of elongate bars extending parallel with the rows of punches 18and interposers 22 and which are on opposite sides of the row ofinterposers and are fixed in the guide block 20, provide a simpleconstruction for yieldably holding the interposers retracted. The rod58, passing through the openings 22a in the interposers, holds theinterposers within the slots 50 and 52 until full disassembly of theinterposers 22 with respect to the guide block 20 is desired.

it is to be understood that the invention is not be limited to thespecific constructions and arrangements shown and described, except onlyinsofar as the claims may be so limited, as it will be apparent to thoseskilled in the art that changes may be made without departing from theprinciples of the invention.

What is claimed is:

l. Thrust transmission mechanism comprising:

a reciprocable work element;

a reciprocable drive element and means for reciprocating the driveelement;

an interposer of magnetic material arranged to move into and out ofalignment with one of said elements, and when in alignment therewith,transmitting thrust from said drive element to said work element;

a magnet disposed in close proximity to and acting magnetically on saidinteiposer for moving it out of a first one of its said positions andinto a second one of its said positions;

a movable thrust rod efi'ective on said interposer for moving theinterposer against the action of said magnet into alignment with saidone element; and

a motor connected to and effective on said thrust rod for moving saidinterposer into alignment with said one element.

2, Thrust transmission mechanism as set forth in claim l and including aplurality of additional reciprocable work elements in addition to saidfirst-named work element, said work elements being in alignment in a rowand the thrust transmission mechanism including also an interposersimilar to said firstnamed interposer and a thrust rod and motor similarto said first-named thrust rod and motor corresponding to each one ofsaid additional work elements, said drive element and said magnet beingeffective on the additional ones of said interposers as on saidfirst'named interposer as aforesaid.

3. Thrust transmission mechanism comprising:

a reciprocable work element:

a reciprocable drive element and means for reciprocating the driveelement:

an interposer arranged to move into aligned position and out of alignedposition with one of said elements and, when in alignment therewith,transmitting thrust from said drive element to said work element, saidinterposer including magnetic material;

a magnet effective magnetically on said interposer for moving it out ofa first one of its said positions into a second one of its saidpositions; and

an actuator for moving said interposer from its said second positionback to its said first position, said thrust transmission mechanismincluding a plurality of additional reciprocable work elements inaddition to said firstnamed work element, said work elements being inalignment in a row and the thrust transmission mechanism including alsoan interposer similar to said first-named interposer and an actuatorsimilar to said first-named actuator corresponding to each one of saidadditional work elements, said drive element and said magnet beingeffective on the additional ones of said interposers and on saidfirst-named interposer as aforesaid, said interposers being in a rowcorresponding to the row of work elements, said actuators each being inthe form of an oblong shaped, pneumatically actuated piston which hasits major dimension parallel with said interposers, alternate ones ofsaid pistons being disposed on one side of the row of interposers andthe others of said pistons being disposed on the other side of the rowof interposers.

4i Thrust transmission mechanism as set forth in claim 2, said driveelement constituting a bail having a thrust-transmitting edge effectivefor engaging said interposers and extending around said interposers toprovide a one-way engagement with said work elements so as to retractsaid work elements to nonworking positions on reciprocation of saiddrive element.

5. Thrust transmission mechanism comprising:

a reciprocable work element;

a reciprocable drive element and means for reciprocating the driveelement;

an interposer arranged to move into aligned position and out of alignedposition with one of said elements and, when in alignment therewith,transmitting thrust from said drive element to said Work element, saidinterposer including magnetic material;

a magnet effective magnetically on said interposer for moving it out ofa first one of its said positions into the second one ofits saidpositions; and

an actuator for moving said interposer from its second position back toits said first position, said magnet being of a permanenet type andmagnetically moving said interposer out of aligned position with saidone element, said actuator being effective for moving said interposerback into alignment with said one element against the magnetic action ofsaid magnet, said mechanism including a guide block having a slottherein for receiving said interposer, said interposer being of rigidmagnetic material and said slot having parallel sidewalls between whichsaid interposer fits in sliding relationship whereby to pivotally mountsaid interposer in said slot.

6. Thrust transmission mechanism as set forth in claim 5, said mechanismalso including a plurality of work elements similar to said first-namedwork element, said work elements being disposed in a row, said mechanismalso including an interposer and an actuator for each of said additionalwork elements which are similar to said interposer and said actuator forsaid first-named work element, said guide block including additionalslots for said additional interposers similar to said first-named slot,said magnet being effective on substantially one-half of saidinterposers and said mechanism including a second similar magneteffective on the others of said interposers, said magnets being mountedin said guide block and extending parallel to said row of work elements.

7. Thrust transmission mechanism as set forth in claim 6, said magnetsbeing in the form of elongate bars disposed on opposite sides of the rowof work elements and each having its north pole on an edge extendinggenerally parallel with the row of work elements.

8. Thrust transmission mechanism as set forth in claim 1, said magnetbeing of a permanent type and magnetically moving said interposer out ofaligned position with said one element, said thrust rod and motor beingeffective for moving said interposer back into alignment with said oneelement against the magnetic action ofsaid magnet.

9. Thrust transmission mechanism as set forth in claim 8, said oneelement with respect to which said magnet is effective for moving saidinterposer out of alignment constituting said reciprocable drive elementand said thrust rod and motor being effective to move said interposerback into alignment with said reciprocable drive element.

10. Thrust transmission mechanism comprising:

a reciprocable work element;

a reciprocable drive element and means for reciprocating the driveelement;

an interposer arranged to move into aligned position and out of alignedposition with one of said elements and, when in alignment therewith,transmitting thrust from said drive element to said work element, saidinterposer including magnetic material;

a magnet effective magnetically on said interposer for moving it out ofafirst one of its said positions into the second one of its saidpositions; and

an actuator for moving said interposer from its said second positionback to its said first position;

said magnet being of a permanent type and magnetically moving saidinterposer out of aligned position with said one element;

said actuator being effective for moving said interposer back intoalignment with said one element against the magnetic action of saidmagnet, said one element with respect to which said magnet is effectivefor moving said interposer out of alignment constituting saidreciprocable drive element and said actuator being effective to movesaid interposer back into alignment with said reciprocable driveelement;

said interposer being of rigid magnetic material and being pivotallymounted at one end to be in permanent alignment with said work element;

said actuator being effective on the other end of said interposer formoving it into alignment with said drive element.

ll. Thrust transmission mechanism as set forth in claim 10, said workelement constituting a punch and said mechanism including a die intowhich said punch is thrust when said actuator is effective for movingsaid interposer,

l2. Thrust transmission mechanism as set forth in claim 10 and includinga plurality of additional reciprocable work elements in addition to saidfirst-named work element, said work elements being in alignment in a rowand the thrust transmission mechanism including also an interposersimilar to said first-named interposer and an actuator similar to saidfirstnamed actuator corresponding to each one of said additional workelements, said drive element being effective on all of said interposersand said magnet also being efiective on substantially oneehalf of saidinterposers, said mechanism also including a second magnet which iseffective on the others of said interposers.

13. Thrust transmission mechanism as set forth in claim 10, said driveelement including a bail which is interconnected

1. Thrust transmission mechanism comprising: a reciprocable workelement; a reciprocable drive element and means for reciprocating thedrive element; an interposer of magnetic material arranged to move intoand out of alignment with one of said elements, and when in alignmenttherewith, transmitting thrust from said drive element to said workelement; a magnet disposed in close proximity to and acting magneticallyon said interposer for moving it out of a first one of its saidpositions and into a second one of its said positions; a movable thrustrod effective on said interposer for moving the interposer against theaction of said magnet into alignment with said one element; and a motorconnected to and effective on said thrust rod for moving said interposerinto alignment with said one element.
 2. Thrust transmission mechanismas set forth in claim 1 and including a plurality of additionalreciprocable work elements in addition to said first-named work element,said work elements being in alignment in a row and the thrusttransmission mechanism including also an interposer similar to saidfirst-named interposer and a thrust rod and motor similar to saidfirst-named thrust rod and motor corresponding to each one of saidadditional work elements, said drive element and said magnet beingeffective on the additional ones of said interposers as on saidfirst-named interposer as aforesaid.
 3. Thrust transmission mechanismcomprising: a reciprocable work element: a reciprocable drive elementand means for reciprocating the drive element: an interposer arranged tomove into aligned position and out of aligned position with one of saidelements and, when in alignment therewith, transmitting thrust from saiddrive element to said work element, said interposer including magneticmaterial; a magnet effective magnetically on said interposer for movingit out of a first one of its said positions into a second one of itssaid positions; and an actuator for moving said interposer from its saidsecond position back to its said first position, said thrusttransmission mechanism including a plurality of additional reciprocablework elements in addition to said first-named work element, said workelements being in alignment in a row and the thrust transmissionmechanism including also an interposer similar to said first-namedinterposer and an actuator similar to said first-named actuatorcorresponding to each one of said additional work elements, said driveelement and said magnet being effective on the additional ones of saidinterposers and on said first-named interposer as aforesaid, saidinterposers being in a row corresponding to the row of work elements,said actuators each being in the form of an oblong shaped, pneumaticallyactuated piston which has its major dimension parallel with saidinterposers, alternate ones of said pistons being disposed on one sideof the row of interposers and the others of said pistons being disposedon the other side of the row of interposers.
 4. Thrust transmissionmechanism as set forth in claim 2, said drive element constituting abail having a thrust-transmitting edge effEctive for engaging saidinterposers and extending around said interposers to provide a one-wayengagement with said work elements so as to retract said work elementsto nonworking positions on reciprocation of said drive element. 5.Thrust transmission mechanism comprising: a reciprocable work element; areciprocable drive element and means for reciprocating the driveelement; an interposer arranged to move into aligned position and out ofaligned position with one of said elements and, when in alignmenttherewith, transmitting thrust from said drive element to said workelement, said interposer including magnetic material; a magnet effectivemagnetically on said interposer for moving it out of a first one of itssaid positions into the second one of its said positions; and anactuator for moving said interposer from its second position back to itssaid first position, said magnet being of a permanenet type andmagnetically moving said interposer out of aligned position with saidone element, said actuator being effective for moving said interposerback into alignment with said one element against the magnetic action ofsaid magnet, said mechanism including a guide block having a slottherein for receiving said interposer, said interposer being of rigidmagnetic material and said slot having parallel sidewalls between whichsaid interposer fits in sliding relationship whereby to pivotally mountsaid interposer in said slot.
 6. Thrust transmission mechanism as setforth in claim 5, said mechanism also including a plurality of workelements similar to said first-named work element, said work elementsbeing disposed in a row, said mechanism also including an interposer andan actuator for each of said additional work elements which are similarto said interposer and said actuator for said first-named work element,said guide block including additional slots for said additionalinterposers similar to said first-named slot, said magnet beingeffective on substantially one-half of said interposers and saidmechanism including a second similar magnet effective on the others ofsaid interposers, said magnets being mounted in said guide block andextending parallel to said row of work elements.
 7. Thrust transmissionmechanism as set forth in claim 6, said magnets being in the form ofelongate bars disposed on opposite sides of the row of work elements andeach having its north pole on an edge extending generally parallel withthe row of work elements.
 8. Thrust transmission mechanism as set forthin claim 1, said magnet being of a permanent type and magneticallymoving said interposer out of aligned position with said one element,said thrust rod and motor being effective for moving said interposerback into alignment with said one element against the magnetic action ofsaid magnet.
 9. Thrust transmission mechanism as set forth in claim 8,said one element with respect to which said magnet is effective formoving said interposer out of alignment constituting said reciprocabledrive element and said thrust rod and motor being effective to move saidinterposer back into alignment with said reciprocable drive element. 10.Thrust transmission mechanism comprising: a reciprocable work element; areciprocable drive element and means for reciprocating the driveelement; an interposer arranged to move into aligned position and out ofaligned position with one of said elements and, when in alignmenttherewith, transmitting thrust from said drive element to said workelement, said interposer including magnetic material; a magnet effectivemagnetically on said interposer for moving it out of a first one of itssaid positions into the second one of its said positions; and anactuator for moving said interposer from its said second position backto its said first position; said magnet being of a permanent type andmagnetically moving said interposer out of aligned position with saidone element; said actuator being effective for moving said interposerback into alignment with said one element against the magnetic action ofsaid magnet, said one element with respect to which said magnet iseffective for moving said interposer out of alignment constituting saidreciprocable drive element and said actuator being effective to movesaid interposer back into alignment with said reciprocable driveelement; said interposer being of rigid magnetic material and beingpivotally mounted at one end to be in permanent alignment with said workelement; said actuator being effective on the other end of saidinterposer for moving it into alignment with said drive element. 11.Thrust transmission mechanism as set forth in claim 10, said workelement constituting a punch and said mechanism including a die intowhich said punch is thrust when said actuator is effective for movingsaid interposer.
 12. Thrust transmission mechanism as set forth in claim10 and including a plurality of additional reciprocable work elements inaddition to said first-named work element, said work elements being inalignment in a row and the thrust transmission mechanism including alsoan interposer similar to said first-named interposer and an actuatorsimilar to said first-named actuator corresponding to each one of saidadditional work elements, said drive element being effective on all ofsaid interposers and said magnet also being effective on substantiallyone-half of said interposers, said mechanism also including a secondmagnet which is effective on the others of said interposers.
 13. Thrusttransmission mechanism as set forth in claim 10, said drive elementincluding a bail which is interconnected with said work element forpulling said work element back to a nonworking position on reciprocationof said drive element.
 14. Thrust transmission mechanism as set forth inclaim 13, said actuator constituting a pneumatically actuated piston.